Input wants to be assigned and constrained as Clock

Why not post the code so we can have a proper look?

And also - its very bad practice to have an "else" clause next to a clock. You get away with it because you just tell the code to hold the value, but if there was anything else in there the synthesisor would throw and error for bad synchronous description. You also only need the clock signal in the sensitivity list, the rest are redundant (and technically slow your simulator down).